


Keep a Secret

by MidnightsNightmares



Category: Undertale (Video Game)
Genre: F/M, Frisk Has a Nightmare, Sans Sings Frisk a Lullaby, and now i headcanon this so hard like im gonna cry, i want ALL of the singing headcanons about sans, so i saw the post about singing sans with drop pop candy
Language: English
Status: Completed
Published: 2015-11-29
Updated: 2015-11-29
Packaged: 2018-05-03 22:15:39
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,655
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5309066
Author URL: https://archiveofourown.org/users/MidnightsNightmares/pseuds/MidnightsNightmares
Summary: <blockquote class="userstuff">
              <p>Sans doesn't typically get up in the middle of the night over noises, but when he hears Frisk crying in the other room he decides to share a secret talent he has to them.</p>
            </blockquote>





	Keep a Secret

Sans woke up when he thought he heard someone crying.

  
He isn't one to rise up out of a comfy spot in the middle of the night just because of the strange noise. Typically he would write it off as Papyrus or the wind before rolling over and going back to sleep with a loud snore. He wasn't about to lose a precious five minutes of shut eye the nights he doesn't have those awful, awful nightmares just because of some random noise sounding out through the house. If it was repetitive and ominous, he couldn't bother with it unless it sounded dangerous. Eventually, he might have been concerned if it did sound dangerous, but it still wouldn't prompt him to get out of bed.

  
But this was the tears of a child he was helping take care of.

  
Frisk must have been awake. He wondered if Toriel would hear them eventually but it seemed after a few minutes of laying there and waiting, wide awake himself, that she was in a deep sleep. Enough that she couldn't hear her child was in distress over something.

  
Sans didn't stay over much when they'd first come to the surface but bonding with Toriel, getting closer to her and developing a small, small crush on her made him feel as if he wanted to be around her a lot more. She didn't really seem bothered by the company, as he felt after the first few times of staying with them might have been seen as too clingy, but he wasn't. She'd tidy up the guest room and he'd sleep there for the night while Papyrus did whatever back at their house. The guest room was right cross from Frisk's room, and Toriel's at the end of the hall.

  
He waited another moment or so before he sighed and got up. He knew he couldn't go back to sleep hearing them in their room, so he forced himself to get over the laziness biting at his bones to at least check in on them. He was sure to be quiet, tossing the soft blankets off of him and slipped on the slippers next to the bed. His jacket was tossed carelessly over the back of the chair in the corner of the room, and he didn't care enough to walk over there and get it despite the slight thought hanging in the back of his mind to slip it on.

  
Opening the door and walking across the hall, he was sure to be gentle when he opened the door to Frisk's room.

  
Frisk was sitting up in their bed, but their head was down and they didn't really seem to react when he came into the room. It was when he shut the door behind him that Frisk raised their head to look at him with surprise. Sans merely walked towards the bed, trying to create a calming aura but that's never really been his own personal atmosphere that he gave off. He gave an environment where things should be bustling with joy, not peaceful and silent. He wasn't a rough, hard-skulled person that would charge at a person either. Sans was something more in the middle. Chaotic if he wanted to be, but otherwise neutral.

  
"Hey, kiddo," he said, walking towards the bed, sitting on the edge of it. "You okay?"

  
They shook their head.

  
"Bad dream?"

  
A nod.

  
"...Heh. Yeah, I get lots of those too. They can be scary, huh?"

  
Another nod. Sans wouldn't be surprised if Frisk could see into other timelines like him, but being so young and being the merciful kind child they were, it could probably scare them into questioning themself, which is the last thing Sans wanted. They shouldn't need to after all of this time. All of the mercy, all of the bonding, all of the saving - it would go to waste if the child ended up in a belief that they were something they were not. Whatever that thing was that crawled out of the black pit of hell and wore Frisk's face like it was nothing was disgusting, and would certainly never be Frisk.  
  
  
Taking another look at their wet cheeks and red eyes, Sans thought about something for a moment. He hesitated over the idea he presented to himself, unsure of it would be helpful at the moment as making Frisk talk about the nightmare didn't really seem that good of an option, but eventually he decided to go for it seeing as the room was now silent.

   
"...Well, get comfy," Sans said. "It probably won't be much, but...I'll share a secret with ya."

  
Frisk looked at him with curious eyes and Sans winked at them. They shuffled to lay back down on the bed, and settled back down in their warm blankets. Sans tried to mimick Toriel for a moment or two, tucking the blankets in around them but it just didn't look snug and comforting like Toriel could do.  
  
  
Well, he was trying, he supposed. He couldn't be something like a father maybe, but he was still family to Frisk. Ever since coming to the surface he'd noticed that Frisk had taken a liking to nearly everyone they'd met, but beyond friendship. It wasn't just him and Papyrus. He knew this child had no family when they dropped to the Underground, so they were all they had. That didn't exclude people like Muffet, Mettaton, Undyne and others like that because they all were sure to see Frisk every so often and check in with everyone else in the Underground. Every friend they had made were all contributing to the growth of themself, but not as much as Toriel was.  
  
  
Though, the first time Frisk ever reached out to him that day and called him 'brother!', he was shocked. He just remembered lifting Frisk into his hold, giving them a hug and a small happy laugh coming out by accident. For some reason, it made him happy to hear.

  
"Since your _bones_ are all _rattled_ ," he said, and felt somewhat successful with Frisk giggled. "My secret is...something only one person knows. Papyrus promised long ago he wouldn't tell anyone, so...will you too?" He asked, holding out his pinky. The child eyed it for a moment before wriggling their hand out from under their blankets and extended their own without hesitation, and with a smile nodded.

  
"Good. Now close your eyes."

  
They did so.

  
Sans hadn't really expressed this part of himself much. Really, out of the minimal things that brought him joy long ago before the resets struck his life, singing was at the top. He remembered the days he'd go around Snowdin, singing whatever song had wormed its way into his mind loudly and proudly. He'd sung at Grillby's, and even a few times at MTT Resort. Many were impressed, even Papyrus was, but eventually he'd stopped.

  
Singing hadn't been so enjoyable after the resets begun, because no one would ever remember he could.

  
It wasn't like he didn't sing after the resets started, it's that he stopped doing it in front of other people. It became repetition after a while and eventually just hummed and sang to himself whenever he was alone. It seemed though that no matter what timeline they were in that Papyrus seemed destined to figure it out from him. Sometimes Papyrus would bother him to sing but the old memories would flood in, and then everyone forgetting it would remind him it was pointless, so he'd always reject.

  
Frisk seemed to like music, and seeing as Sans wasn't always the best with his words sometimes, he supposed humming something soft for the kid wouldn't be too bad. He knew Frisk typically kept promises so he hoped this was something they didn't think was brag-worthy.

  
It was no particular tune either at first; whatever came to mind came out of his voice, and eventually an old, old song came to thought. It was a warm, happy song that he'd sung to Papyrus in the past when he was a baby to ease him to sleep and suddenly a jolt of something warm was sent through his bones. It was an odd feeling at first but it was something he's felt in the past that was unmistakable.

  
A warm feeling of happiness. He wasn't sure it was because he was singing again to someone, or if it was because he remembered that memory. A mixture of both. He'd easily eased himself into that song, and hummed it. Frisk seemed surprised, likely expecting something like Sans whispering them an actual, devious secret of his. It even prompted them opening their eyes to look at him in surprise before they closed them again at the relaxing tune. Sans almost laughed, but resisted.

  
He hadn't done this in so long. It felt nice, even if he missed the days where he'd get over his own lazy tendencies to sing for the people at Grillby's.

  
Well, who's to say it's too late to change?

  
Sans had seen the human had fallen to relax, near sleepy but determined to hear the rest of his song. Eventually Sans decided he was done, and that was enough for him for the time being. He was expecting his vocals to be sort of rough from not singing in so long but they were fine, and he grinned to himself as he gently patted Frisk's foot under their blanket, whispering a soft 'good night' to them as he rose from the bed again. He wasn't sure if they were sleeping, but they seemed relaxed enough to do so.

  
He exited the room as quietly as he'd come in and went back to his own, flopping back on the bed with a big breath.

  
He'd have to consider, just maybe next time they all decided to get together, to do something else for entertainment instead of making jokes. 

**Author's Note:**

> I will roll in the life of believing in singing Sans tbh
> 
> itstrickstersugar.tumblr.com


End file.
